Fafard makes an excellent, finely-screened seed starting mix that can't be beat. Wets easily, doesn't compact excessively and has no sticks or other debris to block seedlings from sprouting. The problem is that I don't think Fafard products are as widely distributed as the big name retail products, since much of their business caters to commercial growers.
If you can find it, you won't be disappointed!
Link to the product mentioned above:
http://www.fafard.com/index.php?p=136